Magnetotransport Properties of Ferromagnetic Nanoparticles in a Semiconductor Matrix Studied by Precise Size-Selective Cluster Ion Beam Deposition

Abstract

The combination of magnetic and semiconducting properties in one material system has great potential for integration of emerging spintronics with conventional semiconductor technology. One standard route for the synthesis of magnetic semiconductors is doping of semiconductors with magnetic atoms. In many semiconductor–magnetic–dopant systems, the magnetic atoms form precipitates within the semiconducting matrix. An alternative and controlled way to realize such nanocomposite materials is the assembly by codeposition of size-selected cluster ions and a semiconductor. Here we follow the latter approach to demonstrate that this fabrication route can be used to independently study the influence of cluster concentration and cluster size on magneto-transport properties. In this case we study Fe clusters composed of approximately 500 or 1000 atoms softlanded into a thermally evaporated amorphous Ge matrix. The analysis of field and temperature dependent transport shows that tunneling processes affected by Coulomb blockade dominate at low temperatures. The nanocomposites show saturating tunneling magnetoresistance, additionally superimposed by at least one other effect not saturating upon the maximum applied field of 6 T. The nanocomposites’ resistivity and the observed tunneling magnetoresistance depend exponentially on the average distance between cluster surfaces. On the contrary, there is no notable influence of the cluster size on the tunneling magnetoresistance.

Purcell-induced suppression of superradiance for molecular overlayers on noble atom surfaces

“…for the coincidence case. According to the construction of the sand p-wave scattering matrices, M and N, respectively, the vectorial dependence of the Green function can be written as G (1) sp = A rr e r e r + A rϑ e r e ϑ +A ϑr e ϑ e r + A ϑϑ e ϑ e ϑ + A ϕϕ e ϕ e ϕ ,…”

“…Organic photovoltaics and optoelectric devices, in which optical properties arise from the response of molecular complexes, aggregates or nanostructures, have attracted much attention. [1][2][3][4]. Recent investigations on the photoexcitationdriven processes in such systems [5,6] aim to increase of the efficiency of organic solar cells [7,8], for instance by exploiting concepts such as singlet fission.…”

“…induced by each molecule [equal positions Im g(r, r): local-mode density] and a cavity-like resonance [different positions Im g(r, r ): collective atom-field coupling constants], where we assumed the in-phase combination of the sheared excitation (1). The scalar Green function g(r, r ) represents the relevant direction of the dyadic Green function due to the orientation of both molecules, which is its perpendicular component in the presence of a surface or its trace in free space.…”

Current Progress of Magnetoresistance Sensors

“…Another geometry of granular MR systems is based on embedding nanoparticles in the non-magnetic matrix (Figure 6) [75]. Fe nanoparticles were deposited on the SiO 2 matrix with the ion beam, which achieved a positive MR at 40% under a large magnetic field (80 kOe) and room temperature [76].…”

Architecturing materials at mesoscale: some current trends

“…In addition. several systems of immiscible combinations, such as Fe x -Ag [201], Fe x -Cr [202] and Fe x -Ge [203] have shown interesting magnetic and magnetoelectric properties. Even applications in quantum technology for magnetic Josephson junctions are being considered [204].…”